6-aryl-4-aminopicolinates, such as methyl 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)picolinate, and 6-aryl-4-amino-5-fluoropicolinates, such as benzyl 4-amino-3-chloro-5-fluoro-6-(4-chloro-2-fluoro-3-methoxyphenyl)picolinate, are high value herbicides recently developed and marketed by Dow AgroSciences LLC. The current syntheses for some 6-aryl-4-aminopicolinates and 6-aryl-4-amino-5-fluoropicolinates involve a multi-step process for coupling the head and tail portions of the molecules via Suzuki coupling. For the synthesis of 6-aryl-4-aminopicolinates, the process typically involves protection of a 4-amino-2-chloropicolinate, for example, acetylation of 4-amino-2-chloropicolinate, to enable a high yield Suzuki coupling with an arylboronic acid. Subsequent deprotection via deacetylation affords the final desired product. This process is represented by the current literature reaction scheme for methyl 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylate shown in part in Scheme 1:

In addition, procedures that do not involve protecting the amine group have been used to prepare 6-aryl-4-aminopicolinates and 2-aryl-6-aminopyrimidine-4-carboxylates from 4-amino-6-chloropicolinates and 6-amino-2-chloropyrimidine-4-carboxylates, respectively, by the Suzuki coupling reactions shown in Scheme 2.

For the reaction sequence shown in Scheme 1, reducing the number of reaction steps would decrease the cost of synthesizing the compounds by eliminating or reducing raw materials, unit operations, equipment, and cycle time. For the reactions shown in Scheme 2, reducing the amount of palladium catalyst required for the Suzuki coupling step would also decrease the cost of synthesizing the compounds. For example, the current Suzuki coupling reaction conditions used to produce 6-aryl-4-aminopicolinates from 4-amino-6-chloropicolinates and 2-aryl-6-aminopyrimidine-4-carboxylates from 6-amino-2-chloropyrimidine-4-carboxylates require palladium catalyst loadings of 4% or higher to produce yields of desired coupled product greater than 60%. Considering the high cost of palladium and the fact that some palladium catalyst will inevitably be lost during the course of the Suzuki coupling reaction and catalyst recycling steps, improved Suzuki coupling reaction conditions that reduce the amount of required palladium catalyst loading to produce 6-aryl-4-aminopicolinates, 6-aryl-4-amino-5-fluoropicolinates, and 2-aryl-6-aminopyrimidine-4-carboxylates in high yield would significantly decrease the cost of producing these classes of molecules.